The present invention relates to a heat exchanger core construction adaptable for use in charged air cooler assemblies for turbo-charged internal combustion engines and, more particularly, to a heat exchanger core construction of the plate and fin type wherein a plurality of identical elongated plate members are joined together in a stackable mating arrangement such that either a single-pass or a double-pass system is formed between each respective pair of plate members so joined depending upon the particular orientation thereof. When two of the present core plate members are joined together in face-to-face relationship, a heat exchanger element is formed having a central flow region therebetween. In one orientation, the mated core plate members form a double-pass flow arrangement therebetween whereas a single-pass flow arrangement may be achieved by simple reorientation of the mating core plate members. The provision for achieving single or double pass fluid flow arrangements by utilizing a universal core plate member significally reduces the tooling requirements for producing a family of heat exchanger constructions as needed for a wide variety of applications.